The Belgian port city of Antwerp is the world capital of diamond-cutting. Over the years, the city's close-knit diamond community has created one of Europe's most secure zones, with some 2,000 surveillance cameras, police monitoring and countless identity controls to protect its $200 million in daily trade of rough and polished gems.

Antwerp, which lies 43 kilometers (27 miles) from the airport, had been hit by a major heist in 2003 and had learned its lesson.

`'We are just about the safest place in Belgium," said Antwerp World Diamond Center spokeswoman Caroline De Wolf.

And once Swiss Flight LX789 was airborne Monday night on its way to Zurich, a cache of diamonds tucked safely in its hold, that would not be a great place for a robbery either.

But the airport's 25-kilometer perimeter fence and the transfer of the diamonds from the security van on the tarmac to the hold of the Fokker 100 twin engine jet -- now that held potential.

After weeks of lashing rain, snow, sleet and black ice, Monday evening was finally was as good as it gets in late winter in Belgium. Crisp, cold air meant dry roads for a perfect getaway, and winter's early darkness was a blessing for those needing stealth.

About 20 minutes before the flight's planned 8:05 p.m. departure, the robbers used a construction site outside the airport fence in which to hide. Then in two black cars with blue police lights flashing, they forced their way through the fence and onto the tarmac, speeding straight to pier A.

That was right where the armored car had just finished transferring the diamonds into the Fokker.

Dressed in dark police clothing and hoods, the thieves halted by the plane, whipped out machine guns and stopped the pilots and the transport security crew in their tracks.

The 29 passengers?

"They saw nothing," Anja Bijnens of the Brussels prosecutor's office said Tuesday. "They never fired a shot. They never injured anyone."

With speed and precision, the thieves opened the plane's hold, picked out 120 parcels and loaded them into the cars.

"Afterward, they made a high-speed getaway," Bijnens said, estimating the whole operation took about five minutes.

By late Tuesday, investigators had found the charred remains of a van most likely used in the heist but little else.